Lipoprotein (a) [Lp(a)] is a critical factor in cardiovascular health, composed of low-density lipoprotein-like particles bound to apolipoprotein (a). Elevated Lp(a) levels are associated with an increased risk of cardiovascular diseases (CVD), accelerating disease progression and raising CVD-related mortality. However, the lack of standardized measurement methods for Lp(a) contributes to diagnostic uncertainties in this area.

A quantitative measurement method for serum Lp(a) was developed using fully automated latex-enhanced particle immunoturbidimetry, marking a significant advancement in diagnostic capabilities. Key parameters, including repeatability, stability, linearity, detection limit, interference, and method comparison, were evaluated to ensure the assay's reliability and accuracy.

Lp(a) in samples was detected by carboxylated latex particles (95 nm in diameter) covalently coated with anti-Lp(a) antibodies. Lp(a) concentration was quantified by measuring the turbidity changes caused by agglutination at 600 nm. This method provides rapid, accurate, and fully automated measurements on the Hitachi 7100 automatic biochemical analyzer. With intra-batch precision CV% of 1.10% and inter-batch precision CV% of 1.79%, the method demonstrates reliable performance with Randox biochemical quality control samples. It has a detection limit of 7 mg/L and a high correlation coefficient (R2 = 0.9946) within the 0-1500 mg/L range. Minimal interference from bilirubin, fat emulsion, hemoglobin, and ascorbic acid was observed. Additionally, it shows strong correlation (R2 = 0.9972) with a commercially available latex-enhanced immunoturbidimetric Lp(a) assay reagent, confirming its comparability and clinical suitability.

The quantitative serum Lp(a) determination method based on latex-enhanced immunoturbidimetry offers numerous advantages. It provides rapid, accurate, and automated results, making it ideal for routine clinical testing. The method effectively measures Lp(a) in serum samples by leveraging the interaction between Lp(a) and latex particles.

Liver cancer, particularly hepatocellular carcinoma (HCC), remains a significant global health challenge due to its high mortality rate and late-stage diagnosis. The discovery of reliable biomarkers is crucial for improving early detection and patient outcomes. This review provides a comprehensive overview of current and emerging biomarkers for HCC, including alpha-fetoprotein, des-gamma-carboxy prothrombin, glypican-3, Golgi protein 73, osteopontin, and microRNAs. Despite advancements, the diagnostic limitations of existing biomarkers underscore the urgent need for novel markers that can detect HCC in its early stages. The review emphasizes the importance of integrating multi-omics approaches, combining genomics, proteomics, and metabolomics, to develop more robust biomarker panels. Such integrative methods have the potential to capture the complex molecular landscape of HCC, offering insights into disease mechanisms and identifying targets for personalized therapies. The significance of large-scale validation studies, collaboration between research institutions and clinical settings, and consideration of regulatory pathways for clinical implementation is also discussed. In conclusion, while substantial progress has been made in biomarker discovery, continued research and innovation are essential to address the remaining challenges. The successful translation of these discoveries into clinical practice will require rigorous validation, standardization of protocols, and cross-disciplinary collaboration. By advancing the development and application of novel biomarkers, we can improve the early detection and management of HCC, ultimately enhancing patient survival and quality of life.

Golgi protein 73 (GP73) is implicated in key pathogenic processes, particularly those related to inflammation and fibrogenesis. In the last years, its measurement has emerged as a promising biomarker for detection of liver fibrosis (LF), a common consequence of chronic liver disease that can progress to cirrhosis and eventually hepatocellular carcinoma. GP73 concentrations in blood appear significantly increased in LF patients, correlating with disease severity, making this biomarker a possible non-invasive alternative for detecting and monitoring this condition regardless of etiology. Understanding the molecular mechanisms involving GP73 expression could also lead to new therapeutic strategies aimed at modulating its synthesis or function to prevent or reverse LF. Despite its clinical potential, GP73 as a LF biomarker faces several challenges. The lack of demonstrated comparability among different assays as well as the lack of knowledge of individual variability can make difficult the result interpretation. Further research is therefore needed focusing on robust clinical validation of GP73 as a LF biomarker. Addressing analytical, biological, and clinical limitations will be critical to exploiting its potential for improving detection and monitoring of advanced LF.

Objective and Impact Statement: This study aims to couple C-reactive protein (CRP) antibodies onto latex spheres of 2 different sizes to enhance the accuracy and sensitivity of CRP detection. Furthermore, it seeks to establish a robust methodological framework crucial for advancing the development of latex-enhanced immunoturbidimetric detection reagents. Introduction: CRP, an acute-phase protein, rapidly elevates in response to infections or tissue damage. Double-particle latex-enhanced immunoturbidimetry offers important advantages for accurately measuring CRP levels. Methods: CRP antibodies were coupled with 2 sizes of polystyrene latex spheres. Coupling rates were evaluated to determine optimal conditions. Particle sizes suitable for CRP detection, as well as coupling and mixing ratios, were optimized using automated biochemical analysis. Transmission electron microscopy and nanoparticle size analysis were employed to characterize the morphology and size changes of CRP antibodies and coupled latex spheres before and after immune reaction. Results: Optimization identified 168- and 80-nm latex sphere sizes, with CRP antibody coupling rates of 92% and 91%, respectively. The optimal ratios were 10:1.5 for large latex spheres to polyclonal antibodies and 5:1.5 for small latex spheres to monoclonal antibodies. A 1:8 mixing ratio of large to small latex spheres was effective. Transmission electron microscopy confirmed uniform sizes postcoupling, maintaining dispersion with no morphological changes. CRP reacted with the double-particle latex reagent, forming immune complexes that exhibited agglutination. Mixed latex spheres showed varied agglutination states with CRP concentration, altering solution absorbance. Conclusion: This study validates the efficacy of the dual-particle-size CRP antibody latex reagent, highlighting its potential for future immunoturbidimetric analysis applications.

Particle-enhanced turbidimetric immunoassay (PETIA) is a new measurement procedure for detecting fecal calprotectin (FC). We aimed to investigate the accuracy and clinical performance of PETIA for FC. We assessed the accuracy of PETIA for FC measurements through concordance analysis, Passing-Bablok regression and Bland-Altman analysis, using enzyme-linked immunosorbent assay (ELISA) as the reference. To evaluate the clinical performance of PETIA, the FC levels of individuals with significant and non-significant bowel diseases were compared. The receiver operating characteristic (ROC) analysis was performed to determine the appropriate cut-off value of FC detected by PETIA for discriminating subjects with significant and non-significant colorectal lesions. Of the 413 cases analyzed, 340 (82.3%) were concordant between PETIA and ELISA. No significant discordance was observed. There was a good agreement (y = -7.710+0.957x) between PETIA and ELISA for detecting FC. The FC level detected by PETIA in patients with significant bowel diseases (159.1 [31.3, 821.0] µg/g) was significantly higher than that of subjects with non-significant bowel diseases (10.3 [4.2, 38.5] µg/g) (p < 0.001). The AUC of FC for identifying significant bowel diseases detected by PETIA was 0.82 (p < 0.001). With a cut-off value of 77.6µg/g, the specificity and positive predictive value were 92.2% and 97.1%, respectively. The PETIA for FC measurement showed good clinical performance for detecting bowel diseases.

Nanodiamonds (NDs) are carbon nanoparticles with a large refractive index, a high density, and exceptional chemical stability. When excited by green light, they can emit bright red fluorescence from implanted nitrogen-vacancy (NV) centers. Taking advantage of these properties, we have developed antibody-conjugated NDs as in vitro diagnostic sensors for two complementary assays: particle-enhanced turbidimetric immunoassay (PETIA) and spin-enhanced lateral flow immunoassay (SELFIA). To achieve this goal, monocrystalline diamond powders (∼100 nm in diameter) with or without NV implantation were first treated in molten KNO3 to reduce their size and shape inhomogeneity, followed by surface carboxylation in strong oxidative acids and non-covalent conjugation with antibodies in water. PETIA and SELFIA were carried out separately with a microplate reader and a magnetically modulated fluorescence analyzer. Using C-reactive protein (CRP) as the target antigen, we found that anti-CRP-conjugated NDs exhibited high colloidal stability over 1 month at 4 °C in buffer solution. The limits of detection for 3 μL of CRP sample solution were 0.06 μg/mL and 1 ng/mL with variation coefficients of less than 10 and 15% for PETIA and SELFIA, respectively. These two methods together provide a detection range of 1 ng/mL-10 μg/mL, potentially useful for clinical applications. This work represents the first practical use of rounded monocrystalline NDs as in vitro diagnostic reagents.

Nanotechnology has attracted much attention, and may become the key to a whole new world in the fields of food, agriculture, building materials, machinery, medicine, and electrical engineering, because of its unique physical and chemical properties, including high surface area and outstanding electrical and optical properties. The bottom-up approach in nanofabrication involves the growth of particles, and we were inspired to propose a novel nanoplasmonic method to detect the formation of nanoparticles in real time. This innovative idea may contribute to the promotion of nanotechnology development. An increase in nanometer particle size leads to optical extinction or density (OD)-value changes in our nanosensor chip at a specific wavelength measured in a generic microplate reader. Moreover, in applying this method, an ultrasensitive nanoplasmonic immunoturbidimetry assay (NanoPITA) was carried out for the high-throughput quantification of hypersensitive C-reactive protein (CRP), a well-known biomarker of cardiovascular, inflammatory, and tumor diseases. The one-step detection of the CRP concentration was completed in 10 min with high fidelity, using the endpoint analysis method. The new NanoPITA method not only produced a linear range from 1 ng/mL to 500 ng/mL CRP with the detection limit reduced to 0.54 ng/mL, which was an improvement of over 1000 times, with respect to regular immunoturbidity measurement, but was also effective in blood detection. This attractive method, combined with surface plasmon resonance and immunoturbidimetry, may become a new technology platform in the application of biological detection.

GP73 is a transmembrane glycoprotein that increases in viral and non-viral liver diseases, especially in hepatocellular carcinoma. This study aims to evaluate the effect of sample type and storage conditions on GP73 concentration. Twenty subjects were enrolled in this study. Serum and citrated plasma samples were collected. Both were subjected to different time intervals and storage temperature. Baseline GP73 concentrations ranged from 1.7 to 16.9 ng/mL in serum samples, and from 1.1 to 15.3 ng/mL in citrated plasma (Mann-Whitney U test, p = .1). The acceptable change limit for GP73 was 6.1%. As the highest value of the median percentage deviation was -5.3% in both sample types at different storage condition so, deviations were within the accepted limits. But there were considerable variations in the GP-73 concentrations after 2 cycles of freezing and thawing at -20 °C. This study shows that both serum and citrated plasma can be used for the measurement of GP73 concentration. GP73 seems to be stable under common storage conditions, but it may be unstable with frequent cycles of freezing and thawing.

Golgi protein 73 (GP73, also referred to as Golph 2) with 400 amino acids is a 73 kDa transmembrane glycoprotein typically found in the cis-Golg complex. It is primarily expressed in epithelial cells, which has been found upregulated in hepatocytes in patients suffering from both viral and non-viral liver diseases. GP73 has drawn increasing attention for its potential application in the diagnosis of liver diseases such as hepatitis, liver cirrhosis and liver cancer. Herein, we reviewed the discovery history of GP73 and summarized studies by many groups around the world, aiming at understanding its structure, expression, function, detection methods and the relationship between GP73 and liver diseases in various settings.